Class-ify ptid_t

I grew a bit tired of using ptid_get_{lwp,pid,tid} and friends, so I decided to
make it a bit easier to use by making it a proper class.  The fields are now
private, so it's not possible to change a ptid_t field by mistake.

The new methods of ptid_t map to existing functions/practice like this:

  ptid_t (pid, lwp, tid) -> ptid_build (pid, lwp, tid)
  ptid_t (pid) -> pid_to_ptid (pid)
  ptid.is_pid () -> ptid_is_pid (ptid)
  ptid == other -> ptid_equal (ptid, other)
  ptid != other -> !ptid_equal (ptid, other)
  ptid.pid () -> ptid_get_pid (ptid)
  ptid.lwp_p () -> ptid_lwp_p (ptid)
  ptid.lwp () -> ptid_get_lwp (ptid)
  ptid.tid_p () -> ptid_tid_p (ptid)
  ptid.tid () -> ptid_get_tid (ptid)
  ptid.matches (filter) -> ptid_match (ptid, filter)

I've replaced the implementation of the existing functions with calls to
the new methods.  People are encouraged to gradually switch to using the
ptid_t methods instead of the functions (or we can change them all in
one pass eventually).

Also, I'm not sure if it's worth it (because of ptid_t's relatively
small size), but I have made the functions and methods take ptid_t
arguments by const reference instead of by value.

gdb/ChangeLog:

	* common/ptid.h (struct ptid): Change to...
	(class ptid_t): ... this.
	<ptid_t>: New constructors.
	<pid, lwp_p, lwp, tid_p, tid, is_pid, operator==, operator!=,
	matches>: New methods.
	<make_null, make_minus_one>: New static methods.
	<pid>: Rename to...
	<m_pid>: ...this.
	<lwp>: Rename to...
	<m_lwp>: ...this.
	<tid>: Rename to...
	<m_tid>: ...this.
	(ptid_build, ptid_get_pid, ptid_get_lwp, ptid_get_tid, ptid_equal,
	ptid_is_pid, ptid_lwp_p, ptid_tid_p, ptid_match): Take ptid arguments
	as references, move comment to class ptid_t.
	* common/ptid.c (null_ptid, minus_one_ptid): Initialize with
	ptid_t static methods.
	(ptid_build, pid_to_ptid, ptid_get_pid, ptid_get_tid,
	ptid_equal, ptid_is_pid, ptid_lwp_p, ptid_tid_p, ptid_match):
	Take ptid arguments as references, implement using ptid_t methods.
	* unittests/ptid-selftests.c: New file.
	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
	unittests/ptid-selftests.c.
	(SUBDIR_UNITTESTS_OBS): Add unittests/ptid-selftests.o.

gdb/gdbserver/ChangeLog:

	* server.c (handle_v_cont): Initialize thread_resume::thread
	with null_ptid.

1 files changed, 153 insertions, 0 deletions

diff --git a/gdb/unittests/ptid-selftests.c b/gdb/unittests/ptid-selftests.c
new file mode 100644
index 0000000..5fc2ca6
--- /dev/null
+++ b/gdb/unittests/ptid-selftests.c
@@ -0,0 +1,153 @@
+/* Self tests for ptid_t for GDB, the GNU debugger.
+
+   Copyright (C) 2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "common/ptid.h"
+#include <type_traits>
+
+namespace selftests {
+namespace ptid {
+
+/* Check that the ptid_t class is POD.
+
+   This is a requirement for as long as we have ptids embedded in
+   structures allocated with malloc. */
+
+static_assert (std::is_pod<ptid_t>::value, "ptid_t is POD");
+
+/* We want to avoid implicit conversion from int to ptid_t.  */
+
+static_assert (!std::is_convertible<int, ptid_t>::value,
+	       "constructor is explicit");
+
+/* Build some useful ptids.  */
+
+static constexpr ptid_t pid = ptid_t (1);
+static constexpr ptid_t lwp = ptid_t (1, 2, 0);
+static constexpr ptid_t tid = ptid_t (1, 0, 2);
+static constexpr ptid_t both = ptid_t (1, 2, 2);
+
+/* Build some constexpr version of null_ptid and minus_one_ptid to use in
+   static_assert.  Once the real ones are made constexpr, we can get rid of
+   these.  */
+
+static constexpr ptid_t null = ptid_t::make_null ();
+static constexpr ptid_t minus_one = ptid_t::make_minus_one ();
+
+/* Verify pid.  */
+
+static_assert (pid.pid () == 1, "pid's pid is right");
+static_assert (lwp.pid () == 1, "lwp's pid is right");
+static_assert (tid.pid () == 1, "tid's pid is right");
+static_assert (both.pid () == 1, "both's pid is right");
+
+/* Verify lwp_p.  */
+
+static_assert (!pid.lwp_p (), "pid's lwp_p is right");
+static_assert (lwp.lwp_p (), "lwp's lwp_p is right");
+static_assert (!tid.lwp_p (), "tid's lwp_p is right");
+static_assert (both.lwp_p (), "both's lwp_p is right");
+
+/* Verify lwp.  */
+
+static_assert (pid.lwp () == 0, "pid's lwp is right");
+static_assert (lwp.lwp () == 2, "lwp's lwp is right");
+static_assert (tid.lwp () == 0, "tid's lwp is right");
+static_assert (both.lwp () == 2, "both's lwp is right");
+
+/* Verify tid_p.  */
+
+static_assert (!pid.tid_p (), "pid's tid_p is right");
+static_assert (!lwp.tid_p (), "lwp's tid_p is right");
+static_assert (tid.tid_p (), "tid's tid_p is right");
+static_assert (both.tid_p (), "both's tid_p is right");
+
+/* Verify tid.  */
+
+static_assert (pid.tid () == 0, "pid's tid is right");
+static_assert (lwp.tid () == 0, "lwp's tid is right");
+static_assert (tid.tid () == 2, "tid's tid is right");
+static_assert (both.tid () == 2, "both's tid is right");
+
+/* Verify is_pid.  */
+
+static_assert (pid.is_pid (), "pid is a pid");
+static_assert (!lwp.is_pid (), "lwp isn't a pid");
+static_assert (!tid.is_pid (), "tid isn't a pid");
+static_assert (!both.is_pid (), "both isn't a pid");
+static_assert (!null.is_pid (), "null ptid isn't a pid");
+static_assert (!minus_one.is_pid (), "minus one ptid isn't a pid");
+
+/* Verify operator ==.  */
+
+static_assert (pid == ptid_t (1, 0, 0), "pid operator== is right");
+static_assert (lwp == ptid_t (1, 2, 0), "lwp operator== is right");
+static_assert (tid == ptid_t (1, 0, 2), "tid operator== is right");
+static_assert (both == ptid_t (1, 2, 2), "both operator== is right");
+
+/* Verify operator !=.  */
+
+static_assert (pid != ptid_t (2, 0, 0), "pid isn't equal to a different pid");
+static_assert (pid != lwp, "pid isn't equal to one of its thread");
+static_assert (lwp != tid, "lwp isn't equal to tid");
+static_assert (both != lwp, "both isn't equal to lwp");
+static_assert (both != tid, "both isn't equal to tid");
+
+/* Verify matches against minus_one.  */
+
+static_assert (pid.matches (minus_one), "pid matches minus one");
+static_assert (lwp.matches (minus_one), "lwp matches minus one");
+static_assert (tid.matches (minus_one), "tid matches minus one");
+static_assert (both.matches (minus_one), "both matches minus one");
+
+/* Verify matches against pid.  */
+
+static_assert (pid.matches (pid), "pid matches pid");
+static_assert (lwp.matches (pid), "lwp matches pid");
+static_assert (tid.matches (pid), "tid matches pid");
+static_assert (both.matches (pid), "both matches pid");
+static_assert (!ptid_t (2, 0, 0).matches (pid), "other pid doesn't match pid");
+static_assert (!ptid_t (2, 2, 0).matches (pid), "other lwp doesn't match pid");
+static_assert (!ptid_t (2, 0, 2).matches (pid), "other tid doesn't match pid");
+static_assert (!ptid_t (2, 2, 2).matches (pid), "other both doesn't match pid");
+
+/* Verify matches against exact matches.  */
+
+static_assert (!pid.matches (lwp), "pid matches lwp");
+static_assert (lwp.matches (lwp), "lwp matches lwp");
+static_assert (!tid.matches (lwp), "tid matches lwp");
+static_assert (!both.matches (lwp), "both matches lwp");
+static_assert (!ptid_t (2, 2, 0).matches (lwp), "other lwp doesn't match lwp");
+
+static_assert (!pid.matches (tid), "pid matches tid");
+static_assert (!lwp.matches (tid), "lwp matches tid");
+static_assert (tid.matches (tid), "tid matches tid");
+static_assert (!both.matches (tid), "both matches tid");
+static_assert (!ptid_t (2, 0, 2).matches (tid), "other tid doesn't match tid");
+
+static_assert (!pid.matches (both), "pid matches both");
+static_assert (!lwp.matches (both), "lwp matches both");
+static_assert (!tid.matches (both), "tid matches both");
+static_assert (both.matches (both), "both matches both");
+static_assert (!ptid_t (2, 2, 2).matches (both),
+	       "other both doesn't match both");
+
+
+} /* namespace ptid */
+} /* namespace selftests */